Index: head/sys/dev/sfxge/common/efsys.h
===================================================================
--- head/sys/dev/sfxge/common/efsys.h
+++ head/sys/dev/sfxge/common/efsys.h
@@ -786,6 +786,14 @@
 		EFSYS_PROBE2(bar_writed, unsigned int, (_offset),	\
 		    uint32_t, (_edp)->ed_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the dword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_dword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_edp)->ed_u32[0]);			\
@@ -809,6 +817,14 @@
 		    uint32_t, (_eqp)->eq_u32[1],			\
 		    uint32_t, (_eqp)->eq_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the qword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eqp)->eq_u64[0]);			\
@@ -829,9 +845,25 @@
 		    uint32_t, (_eqp)->eq_u32[1],			\
 		    uint32_t, (_eqp)->eq_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the qword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eqp)->eq_u32[0]);			\
+		/*							\
+		 * It should be guaranteed that the last dword comes	\
+		 * the last, so barrier entire qword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 4, (_eqp)->eq_u32[1]);			\
@@ -858,9 +890,25 @@
 		    uint32_t, (_eop)->eo_u32[1],			\
 		    uint32_t, (_eop)->eo_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the oword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eop)->eo_u64[0]);			\
+		/*							\
+		 * It should be guaranteed that the last qword comes	\
+		 * the last, so barrier entire oword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 8, (_eop)->eo_u64[1]);			\
@@ -888,6 +936,14 @@
 		    uint32_t, (_eop)->eo_u32[1],			\
 		    uint32_t, (_eop)->eo_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the oword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eop)->eo_u32[0]);			\
@@ -897,6 +953,14 @@
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 8, (_eop)->eo_u32[2]);			\
+		/*							\
+		 * It should be guaranteed that the last dword comes	\
+		 * the last, so barrier entire oword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 12, (_eop)->eo_u32[3]);			\